I usually charge $7.25 through paypal. it doesn't sound like alot but I get far more people commissioning me with cash than I ever did before.

EDIT: Also I charge two portspaces instead of one. If you charge one space, everyone is going to pay with spaces. Period. The value of spaces came down from $10.00 to $5.00 when furcadia made the 6 spaces for $30.00 deal permenant.